The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 03, 1997
Filed:
May. 24, 1994
Schuyler E Shimanek, Albuquerque, NM (US);
Alma Anderson, Rio Rancho, NM (US);
Philips Electronics North America Corporation, New York, NY (US);
Abstract
A programmable logic device (PLD) integrated circuit containing an array of fuse or anti-fuse links includes verification circuitry configured to classify link resistances after programing into three resistance zones, corresponding to a 'closed' state zone, an 'open' state zone and a 'forbidden' state zone intermediate the 'closed' and 'open' state zones. Two reference resistance values, namely a lower reference resistance value and the higher reference resistance value, divide the entire range of possible link resistance values into the aforementioned three resistance zones. Because the ratio between the higher reference resistance value and the lower reference resistance value is typically more than 50, the verification circuitry includes a switchable two level current source that produces a voltage across the link of correct dynamic range. A measurement voltage produced in response to the link voltage is compared by a pair of differential comparators to respective lower and higher reference voltages, the lower reference voltage corresponding to the measurement voltage that would be produced by a higher link voltage that is the product of the higher reference resistance value and the lower current level, and the higher reference voltage corresponding to the measurement voltage that would be produced by a lower link voltage that is the product of the lower reference resistance value and the higher current level.